At first glance, Butterfly, which starts later this month on ITV, uses a well-worn mainstream drama set-up. Vicky, played by Anna Friel, is an amiable but troubled mum who lives in an airy, pleasantly middle-class semi. Her career plans are uncertain, her mother (Alison Steadman) is a judgmental hindrance, and her estranged husband (Emmett J Scanlan) has started picking up their two kids for the weekend with his new girlfriend waiting in the car.

All that is thrown into relief when the beginning of secondary school finally prompts the family’s younger child, Max (Callum Booth-Ford), to publicly identify as Maxine, after years of wearing girls’ clothes at home (this, we learn, is the reason Dad left). With Friel the supportive parent who isn’t sure how to protect her child, and Scanlan the father whose ignorance manifests as aggressive denial, Butterfly is a new addition to a resolutely unglamorous genre: the issue-led drama that aims to break down prejudice and ignorance. The question mark hanging over any such project being whether it can be dramatically compelling as well as a force for social good: can it entertain as well as educate?

Like the debate around trans rights and equality, the number of trans characters on TV has increased in the past few years. Emmerdale is the latest soap to introduce a trans storyline, with the addition in June of Ash Palmisciano as Matty, formerly known as Hannah. Boy Meets Girl became the BBC’s first comedy with a trans lead performer, Rebecca Root, in 2015. In the US, where Orange Is the New Black’s Laverne Cox became the first trans actor to be nominated for an Emmy in 2014, the Ryan Murphy drama Pose this year featured a cast dominated by trans performers, while the process of transitioning itself has been tackled by the trailblazing Transparent.

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“Popular media has often portrayed trans people as objects of horror, disgust or as victims,” says the writer, film-maker and non-binary trans campaigner Owl Fisher. “Only in recent years have we started to see trans people represented positively and our real issues and struggles brought forward.”

Butterfly breaks ground by directly addressing children transitioning. “Trans youth are such a vulnerable group and there are many misconceptions around them,” says Fisher. “That’s why Butterfly is massively important: it is authentic representation that humanises us as opposed to demonising us.”

ITV’s three-parter is written by Tony Marchant, a veteran of socially aware TV whose CV includes The Mark of Cain, Public Enemies, Swallow and Kid in the Corner. Marchant forged his scripts after observing meetings organised by Mermaids, a charity that supports gender-diverse and transgender children and young people, and consulting with clinical psychologists at the Tavistock and Portman NHS Foundation Trust.

He says his decision to make Butterfly’s angrily fearful father his main antagonist, but also one who has a shot at redemption, was based on observed reality. “You’d find that the mums were present and the dads were absent. It’s fathers in particular who have an issue. At the same time, [the father’s] worries have to feel nuanced and grounded. He can reasonably say: ‘Look, our child isn’t old enough to make this decision’; possibly it’s a phase, or ‘he’ is actually gay. Those are things most people would regard as normal objections and anxieties. He’s not somebody just bawling prejudices.”

“It is mainly dads who struggle, particularly with kids who identify as female,” agrees Susie Green, CEO of Mermaids and a consultant on Butterfly.

Marchant’s latest work, in other words, fits in with the theme of toxic or fragile masculinity that has run through his whole career. Indeed, it is the fuel for so many acclaimed dramas of box-set TV’s golden age, from The Sopranos and Boardwalk Empire to Mad Men and Dexter. “Men are very caught up in their male identity,” Marchant says, “and where they feel they are when they judge themselves against other men. It’s a problem, still, for men to own up to their vulnerabilities and insecurities.”

Along with the problem of unsympathetic dads, Butterfly confronts another, more controversial, point: the claim that kids exhibiting signs of gender dysphoria are pushed into transitioning. The show is careful to reflect how emotionally fraught the process is; there was no question of casting a trans child actor as Maxine because, according to Green, “it would have forced them to go back to the person they were living as prior to transition: to relive something that was inevitably very painful for them.

“Unfortunately the press gives this impression of children being fast-tracked down a medical route, which isn’t the case,” adds Green. “That’s why Butterfly is so important, it demonstrates that that doesn’t happen.”

“The idea,” says Marchant, “that children are being led down the road of a trans identity – there are parallels between that kind of scaremongering and the idea that we were propagandising our children with a gay sensibility 20 years ago.”

But does Butterfly work as drama? Watching episode one in particular, the viewer is aware of a checklist of points being ticked off, and of characters serving as avatars for the various voices commonly heard. School bullies appear on cue; there’s a scene featuring the perhaps over-vexed question of which public (or in this case, school) toilets to use; and Alison Steadman’s character personifies the stereotype of an older generation who initially just don’t get it.

The primary-colour storytelling palette is, however, intentional. Marchant envisages a family audience, who presumably will watch on catchup since moments of Butterfly are too shocking to air before 9pm. “First, it would be kids going through this, with or without the support of their parents. It’s a positive, affirming message. Then I’d hope it would be parents who aren’t coping with it. After that, maybe just kids with any sort of difference, and their parents. Some sense of: this is what we need to do, this is OK.”

A vivid illustration of the trap to avoid when trying to make issue-led drama edgy is 13 Reasons Why, a US series about a teenager who kills herself, leaving cassette recordings behind to explain her actions. It led to hundreds of critiques with the word “problematic” in the headline – the Washington Post described it as “remarkably, even dangerously, naive in its understanding of suicide” – because its melodramatic tone ended up glamorising suicide as a grand gesture of defiance and revenge. The show was so keen to be eventful and explicit that it became overly traumatising, particularly in the even more heavily criticised second season, which featured a rape and a school shooting in upsetting scenes that didn’t seem to have a solid dramatic purpose.

British primetime’s naturally more prosaic tone, which dates back to Cathy Come Home, the original issue-driven drama in 1966, is safer ground. The best modern yardstick for Butterfly might be The A Word, which nailed the tricky balance between busting social taboos – in that case, about the challenges of bringing up an autistic child – and being an engaging drama.

“The A Word is about communication,” says Lucy Richer, senior commissioning editor for BBC Drama and the show’s executive producer. “It doesn’t pigeon-hole itself as a disability drama. It’s about giving voice to those who might not otherwise be heard, but it tells a relatable story about family. It’s not a drama about autism, it’s a much wider piece, but it feels fresh. Stories about difference should feel fresh, exactly because they’re not familiar.”

The A Word was a medium-sized hit for BBC One, bringing in more than 4 million viewers for last year’s second season. TV is waking up to the fact that audiences are receptive to shows about families coping with difficult or unusual challenges. BBC Four, for instance, has just finished filming There She Goes, starring David Tennant and Jessica Hynes as the parents of a nine-year-old with severe learning disabilities. Such shows can, if done well, comfort and empower those in a similar situation, while moving and enlightening viewers who aren’t.

“I think it just reflects an appetite from people to experience lives that might be different to theirs,” Richer says. “They’re fundamentally about families, and we’ve all grown up in families of different shapes and sizes. It reflects a really open-minded, interested attitude towards understanding experiences. That’s what telly should be doing.” If Butterfly suffers the odd dramatic stumble on its way to passing that test, perhaps it’s a sacrifice worth making.